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Commit 34aed73df3a9e75e313a7510b201f6755ae3e6bc

Authored by Heiko Stübner
Committed by Anton Vorontsov
1 parent ded7fc7b05
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

s3c_adc_battery: Average over more than one adc sample 

Some sources for adc battery information provide only inaccurate results
where the read value differs from the real value with positive and negative
offsets. For such sources it can be more accurate to collect two or more
value sample and use the average of all collected values.

This patch adds pdata options volt_samples, current_samples and
backup_volt_samples to specifiy the number of samples to collect,
reads the specified number of samples and calculates the average of those.
For unset sample-number-values a default of 1 is assumed.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

Showing 2 changed files with 26 additions and 3 deletions Side-by-side Diff

drivers/power/s3c_adc_battery.c
Diff comments   View file @ 34aed73
... ... @@ -47,6 +47,22 @@
47 47 msecs_to_jiffies(JITTER_DELAY));
48 48 }
49 49  
  50 +static int gather_samples(struct s3c_adc_client *client, int num, int channel)
  51 +{
  52 + int value, i;
  53 +
  54 + /* default to 1 if nothing is set */
  55 + if (num < 1)
  56 + num = 1;
  57 +
  58 + value = 0;
  59 + for (i = 0; i < num; i++)
  60 + value += s3c_adc_read(client, channel);
  61 + value /= num;
  62 +
  63 + return value;
  64 +}
  65 +
50 66 static enum power_supply_property s3c_adc_backup_bat_props[] = {
51 67 POWER_SUPPLY_PROP_VOLTAGE_NOW,
52 68 POWER_SUPPLY_PROP_VOLTAGE_MIN,
... ... @@ -67,7 +83,8 @@
67 83 if (bat->volt_value < 0 ||
68 84 jiffies_to_msecs(jiffies - bat->timestamp) >
69 85 BAT_POLL_INTERVAL) {
70   - bat->volt_value = s3c_adc_read(bat->client,
  86 + bat->volt_value = gather_samples(bat->client,
  87 + bat->pdata->backup_volt_samples,
71 88 bat->pdata->backup_volt_channel);
72 89 bat->volt_value *= bat->pdata->backup_volt_mult;
73 90 bat->timestamp = jiffies;
74 91  
... ... @@ -139,9 +156,11 @@
139 156 if (bat->volt_value < 0 || bat->cur_value < 0 ||
140 157 jiffies_to_msecs(jiffies - bat->timestamp) >
141 158 BAT_POLL_INTERVAL) {
142   - bat->volt_value = s3c_adc_read(bat->client,
  159 + bat->volt_value = gather_samples(bat->client,
  160 + bat->pdata->volt_samples,
143 161 bat->pdata->volt_channel) * bat->pdata->volt_mult;
144   - bat->cur_value = s3c_adc_read(bat->client,
  162 + bat->cur_value = gather_samples(bat->client,
  163 + bat->pdata->current_samples,
145 164 bat->pdata->current_channel) * bat->pdata->current_mult;
146 165 bat->timestamp = jiffies;
147 166 }
include/linux/s3c_adc_battery.h
Diff comments   View file @ 34aed73
... ... @@ -25,6 +25,10 @@
25 25 const unsigned int current_channel;
26 26 const unsigned int backup_volt_channel;
27 27  
  28 + const unsigned int volt_samples;
  29 + const unsigned int current_samples;
  30 + const unsigned int backup_volt_samples;
  31 +
28 32 const unsigned int volt_mult;
29 33 const unsigned int current_mult;
30 34 const unsigned int backup_volt_mult;